From the Magazine

'Sea Butterflies' Are a Canary for Ocean Acidification

Researchers aboard a 2011 cruise found severe damage to shells of Limacina helicina, a sea snail that plays an important role in the ecosystem of the California Current off the Pacific coast. Scientists estimate that one-fifth of the pteropods had damaged shells in preindustrial times, owing to the natural acidity of the water, and anthropogenic emissions of CO2 made the water more acidic, more than doubling the number of individuals with damaged shells.